A copper-based catalyst has been widely used for stream reforming of methanol, methanol synthesis, water-gas shift reaction, hydrogenaration and hydrocracking of organic compounds, and the like. However, in general, since a copper-based catalyst has very inferior heat resistance and durability, conditions for the use thereof have been often limited.
As a method in which fine Al alloy particles are used as a carrier of a copper-based catalyst, a method for manufacturing a catalyst used for steam reforming of methanol has been known (Patent Document 1) in which a melt of an Al—Cu-based alloy (5 to 20 atomic percent of Cu and 4 to 18 atomic percent of at least one alloy element selected from the group consisting of a rare earth element, Fe, Mn, Pd, Co, V, Ag, and Pt) is quenched and solidified to form a ribbon-shaped raw material, followed by decomposition thereof by leaching treatment using acid or alkali into powdered particles, so that the surface layers thereof have a mixed phase composed of innumerable ultrafine copper-based particles and innumerable ultrafine alloy element particles.
In Patent Document 1, as a metal structure of the Al alloy, for example, there may be mentioned an Al supersaturated solid-solution single phase structure, quasicrystalline single phase structure, mixed phase structure of a fine Al crystalline phase and a quasicrystalline phase, mixed phase structure of a fine Al crystalline phase and a fine Al-based intermetallic compound phase, amorphous single phase structure, mixed phase structure of an amorphous phase and a fine Al crystalline phase, and mixed phase structure of an amorphous phase, a fine Al crystalline phase, and a fine Al-based intermetallic compound phase.
In addition, it has been known that quasicrystalline ultrafine Al alloy particles have a high activity in a methanol decomposition reaction (Patent Document 2), and as the above quasicrystalline ultrafine Al alloy, for example, there may be mentioned an Al—Pd(20 to 30 atomic percent) alloy, Al—Cu(18 to 23 atomic percent) —Fe(13 to 15 atomic percent) alloy, Al—Cu(15 to 20 atomic percent) —Co(15 to 20 atomic percent) alloy, Al—Ni(10 to 15 atomic percent) —Co(15 to 20 atomic percent) alloy, Al—Pd(15 to 30 atomic percent)-transition metal(17 atomic percent or less) alloy, Al—Pd(15 to 30 atomic percent)-transition metal(17 atomic percent or less) —B(10 atomic percent or less) alloy, and Al—V(13 to 17 atomic percent) —Cu(15 to 20 atomic percent) alloy.
Furthermore, the inventors of the present invention developed a method for manufacturing a catalyst used for steam reforming of methanol in which a quasicrystalline Al alloy ingot composed of Al, Cu and at least one metal atom selected from the group consisting of Fe, Ru, and Os is pulverized, and alloy particles thus obtained are etched with an aqueous sodium hydroxide solution (Patent Document 3, Non-Patent Documents 1, 2, and 3).
Non-Patent Document 1: Applied catalysis A: General 214, (2001), 237 to 241
Non-Patent Document 2: Journal of Alloys and Compounds 342, (2002), 451 to 454
Non-Patent Document 3: Journal of Alloys and Compounds 342, (2002), 473 to 476
Patent Document 1: Japanese Unexamined Patent Application Publication No. 7-265704 (Japanese Patent No. 3382343)
Patent Document 2: Japanese Unexamined Patent Application Publication No. 7-126702
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2001-276625